Heater controller



Dec. 25, 1928. 1,696,684

0. A. KNOPP HEATER CONTROLLER Filed April 13. 1927 %%%%2%%%%% P1E 2. w 22 z;

INVENTQR ZZ 0/)0 v4 Knapp BY W HIS ATTORNEY 3O .a way t at substantially. uniform heating Patented Dec. 25, 1928.

UNITED sTATEs OTTO A. KNOPP, OF OAKLAN D, CALIFORNIA.

mum conrnoLLER.

:Application filed April 13, 1927. Serial No. 183,551.

This invention relates to electric heating and especially to electric hot plates.

Such hot'plates usually include a mass of material, to which lieat is transferred from a unit that is closely adjacent the material. This material is usually either metallic or ceramic; but under each circumstance, it has considerable mass and takes a substan tial period before its temperature is brought to a satisfactory operatingypoint that is useful for the emission of heat. It is one of the objects of my invention to accelerate this initial heating period.

It'is another object of my invention to provide this function by the useof a thermostat that responds to the temperature attainedby the hot plate body, and that ensures a rapid Heating rate, much higher than the normal, until the operating temperature is reached, at which the hot plate emits heat at the desired rate to cooking utensils or. the like, irrespectively of the temperature of the object heated.

.The thermostat is arranged preferabl to reduce the resistance ofthe unit by s 'ort circuiting a portion of it, .Whereby more 1 current is permitted. to flow, and consequently, more poweris expended in heating the plate. It is another object ofmy invention to .farran 'e the two parts of the unit in such ofthe hot plate is secured independentlyof the' condition of the temperature controlling means.., 7,

invention possesses many other. advantages, and'has other objects which may 'be made more: easily apparent from a consideration of one embodiment of my invention. For this purpose I have shown a form in the drawings accompanying and forming part of the present specification. I shall now proceed to described this form in de-- tail, which illustrates the general principles of my invention, but it is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of my invention is best defined by the append- 7 ed claims.

Referring to the drawings: Figure 1 is a plan view mainly diagrammatic,.0f a typical: hot plate in which my in-- In the present instance, I show a hot plate having a body 11 of ceramic material, in the face of which there is a double spiral groove 12. Over this groove can extend to if desired, a cover plate such as indicated at 19 in Fig. 2.. In the groove 12 is located the coiled heating unit 13 and 15, the two ends bemgarranged at approximately the center of the plate, and being doubled at 66 14., adjacent the outer edge of the plate.

In Fig. 3 I show the wiring of the-unit. It 1s possible to pass. current through the two portions 13 and 15 either in parallel or series, so as to produce either a high or a low degree of energization of the source of heat. This can be accomplished by wellknown switching means. For parallel operation, current is fed n at the common junction 14 through lead 16, and both the free terminals 17 and 18 connectto the other side of the circuit. For series operation, current enters through one ofthe terminals 17 or 18, passes through both portions 13 and 15,

and out through the other of the terminals the proper rate, I arrange to reduce the re-' sistance of unit 13-45, as by short circuiting a portion of it betweencommon point 14 and the points 20 and 21, located respectively on portions 15 and 13. This short circuit is effected by strip 22 that carries a con- Y tact 23 bridging contacts 24 and 25 that are connected to points 20 and 21 and located orfthe lower side of late 11. To complete the short circuit, strip 22 is connected to a common point 14 by lead 26. The bridging contact 23 is arranged to be automatically opened upon the unit attaining the desired rate of emission. For thispurpose, strip 22 is bimetallic, and is in goodthermalcontact with plate 11 and by the aid of boss 27 depending from the lower H surface thereof. lVhen the desired rate of emission is reached, strip 22 flexes downwardly, opening the short circuit by pulling contact 23 away from contacts'24 and 25.

- During the initial heating period, current is thus caused to flow only through the inner rom element 85 portions of coils 1-3 and 15, the outer portions being short-circuited. In this way, it is assured that the heat emission of the unit will be uniform even during the initial heating period. During this initial heating pe- .to inaugurate the desired rate of heat emission from adevice that serves as a source of heat.

. I claim:

1. In an electrical heating device, an electrical heating unit, and means for temporarily increasing the energization of the unit beyond its normal operating .point during the initial heating up period of the unit comprising a thermostat operated in 're sponse to the attainment of the desired rate of heat emission of the unit to decrease its energizationi 2. In an electrical heating device, a heating unit, a body of considerable mass sup- .porting said unit, and means causing ab-.

normal energization of the unit during, the heating up of the body to bring it to the desired rate of heat emission, comprising a thermostat operated in response tov the attainment of the-desired rate of heat emission of the unit, to decrease its energization.

3. In an electric hot plate, a heating unit, a thermostat in thermal contact with the unitand contacts for short circuiting a part of the unit and operated by the thermostat, said thermostat being arranged to open the contacts upon the unit reaching normal heat emission. 4." In'an electric heating device, a support ing body, a heating unit coiled on said body to form'a flat spiral, and contacts for short circuiting oneend of the spiral.

5. In an electric heating device, a supporting body, a heating unit coiled on said body to form a spiral, contacts for short circuiting one end of the spiral, and means for opening the contact-s, responsive to the attainment ,of the desired heat emission. v 4 6. In an electric heating. device, a support- 7 ing body, a heating unit in heat exchange relation therewith, said unit being coiled to form two fiat spirals, joined atone end, and contacts for short circuiting a portion of each of the spirals adjacent the joined ends.

7. In an electric heating device, a supporting body, a heating unit in heat exchage re-' lation therewith, said u'nit being coiled to form'two spirals, joined at one end, contacts for short circuiting a portion of each of the spirals adjacent the joinedends, and means for opening the contacts, responsive tothe attainment of the desired heat emission.

In witness whereof I have hereunto set In hand 7 y OTTO A. KNO'PB. 

